




84 X.—THE GEOMETRIDAE. 
CHAPTER 
ise 
THE GEOMETRIDAE. 
The Geometridae are characterized as follows :— 
The maxillary palpi are obsolete. Fore-wings with vein 1b 
usually furcate, but with lower fork often weak or tending to 
be obsolete, 5 risingimot nearer to 4 than to 6, parallel, 7 and 8 
out of 9. Hind-wings almost always with frenulum, le absent. 
(Plate C., figs. 19 to 64.) 
Imago with fore-wings more or less broad-triangular; hind- 
wings broad-ovate. 
Larva with 10 or 12 legs only (Plate I., figs. 21-23, and 34- 
47; .Plate II., figs. 2-25, 27, 31-33 and 40.) 
Pupa with segments 9 to 11 free; not protruded from cocoon 
in emergence. 
This family exhibits the same inequality of represen- 
tation noticed in the others; three-fourths of the whole 
number of species belong to the sub-family Hydriomenides, 
which is very adequately represented, whilst the Selidose- 
mides and Monocteniades are very imperfectly exhibited, 
and the other sub-families either wholly absent or dicated 
only by one or two casually introduced immigrants. Nearly 
all the local affinities are with the South American region, 
in accordance with the principles already laid down in 
Chapter IIT. ; but the few Monocteniades are mainly related 
to Australian forms. 
The numerous and very varied species comprised in 
this family render it by far the most attractive group of 
the larger Lepidoptera found in New Zealand. As in 
the Noctwidae, the dominant character of the colouring is 
protective, but in the much more brightly coloured Geome- 
tridae the objects chiefly imitated are delicate moss-covered 
tree trunks and beautiful lichens. Many of the species 
are highly variable which lends an additional interest to 
their study, and conveys an impression that they are speci- 
fically more numerous than is actually the case. 
The number of species of Geometridae at present 
known in New Zealand is two hundred and forty-three, 
compared with two hundred and seventy-seven in Britain; 
seven hundred and twenty in Europe, and about two 
thousand three hundred and fifty in the whole of the Palae- 
arctic Region. Contrasted with the British species, those 
found in New Zealand are on the whole much more gaily- 
coloured and handsomer insects, and in this respect the 
family offers a marked contrast to many of the others— 
notably the Butterflies and the Arctiadae. 
Of the known species of Geometridae many are con- 
fined to high mountains, and it is thus probable that 
numerous novelties still await discovery in the mountain 
fastnesses of the south-western portion of the South Island. 
The larvae of the Geometridae usually have only two 
pairs of prolegs which are situated on the tenth and thir- 
teenth segments respectively. In a few genera, however, 
an additional pair is placed on the ninth segment. This 
arrangement of the prolegs compels the insect to arch up 
the middle of its body whilst walking, a habit which has 
given rise to the name Geometer, or carth-measurer. Our 
American friends call these caterpillars ‘‘measuring 
worms,’’ and a familiar English title is ‘‘looper.’’ 
A considerable number of the larvae of the lowland 
species of our Geometridae are now known, and many of 
these are quite as attractive as the perfect insects. There 
is, however, abundant scope for future observers in the 
elucidation of the life-histories of the alpine and _ sub- 
alpine species, which form such an important element in 
the fauna. 
The Geometridae are represented in New Zealand by 
the four following sub-families :— 
1. HYDRIOMENIDES. 3. MONOCTENIADES. 
2. STERRHIDES. 4. SELIDOSEMIDES. 
Sub-family 1—HYDRIOMENIDES. 
The Hydriomenides are thus characterized :— 
Fore-wings: 10 rising separate, anastomosing with 11 and 
9 (forming double areole), or rising out of 11 and anastomosing 
with 9 (forming simple areole). Hind-wings: 5 fully developed, 
parallel to 4, 6,and 7 almost always stalked or connate, 8 anas- 
tomosing with upper margin of cell from near base to beyond 
middle, or seldom approximated only and connected by bar 
beyond middle. (Plate C., figs. 19-43.) 
A very large sub-family of universal distribution, 
equally plentiful in New Zealand. The structure is very 
uniform throughout and the generic distinctions slight. 
Imago with body slender, fore-wings usually broad. 
Ovum broad, oval, rather flattened with usually oval 
reticulations. Larva elongate, slender, with few hairs, 
without prolegs on segments 7 to 9; often imitating live 
or dead twigs and shoots. Pupa usually subterranean. 
This sub-family is represented in New Zealand -by the 
following seventeen genera :— 
1. TATOSOMA, 10. VENUSIA. 
2. ELVIA. , 11. ORTHOCLYDON. 
3. MICRODKES. 12. ASAPHODES. 
4, PHRISSOGONUS. 13. PARADETIS. 
5. CHLOROCLYSTIS. 14. XANTHORHOE. 
6. EUCYMATOGE. 15. NOTORBAS. 
7. HYDRIOMENA. 16. DASYURIS. 
8. ASTHENA. 17. LYTHRIA. 
9. HUCHOECA, 
